Electrical circuit control device panel board with novel insulating means



March 26, 1968 J J. MROWKA 3,375,411

ELECTRICAL CIRCU'IT CONTROL DEVICE PANEL BOARD WITH NOVEL INSULATING MEANS Filed July 5. 1967 2 Sheets-Sheet 1 14 2 nvvmrae. O 7 dose/w a MROW/(A H M CW I March 26, 1968 J. J. MROWKA ELECTRICAL CIRCUIT CONTROL DEVICE PANEL BOA WITH NOVEL INSULATING MEANS 2 Sheets-Sheet 2 Filed July 5, 1967 mvewr'az. dysarx/J/Mawmq WW 7 Arm/aver United States Patent 3,375,411 ELECTRICAL CIRCUIT CONTROL DEVICE PANEL BOARD WITH NOVEL INSULATING MEANS Joseph J. Mrowka, Plainville, Conn., assignor to General Electric Company, a corporation of New York Filed July 3, 1967, Ser. No. 650,671

11 Claims. (Cl. 317-119) ABSTRACT OF THE DISCLOSURE There is disclosed an electrical circuit control device panel board wherein the base or saddle has a generally planar portion upon which are disposed a first layer of insulating material, a second layer of insulating material and a plurality of conductors extending in substantially parallel spaced relationship. The second layer of insulating material has a plurality of apertures therein underlying-each of the conductors and spaced along the length thereof with the apertures being dimensioned and disposed with respect to the conductors so that they extend beyond the side margins of a conductor toward the adjacent conductor. The webs between apertures underlying one of the conductors are offset along the length of the conductors from the webs between apertures underlying the adjacent conductors whereby the distance for travel along the upper surface of the second layer between adjacent conductors is increased substantially.

In the preferred embodiment, the layers of insulating material are provided bysheets which are punched or otherwise formed with the desired apertures or cutouts therein. An insulating member bridges one of the conducto-rs and a contact arm having an end attached to another conductor extends normally to that conductor with its other end disposed on the insulating member. To provide sufficient insulated surface between the contact arm and the conductor underlying the insulating member, side wall portions are provided upon the insulating member. The insulating member desirably has upstanding ribs on the upper surface thereof providing a channel seating the contact arm and may be of sufficient width to provide a pair of channels seating a pair of contact arms with an upstanding center wall portion being disposed between the channels to provide an insulated barrier therebetween. To position the insulating member, desirably the second layer of insulating material has apertures formed therein to opposite sides of the conductor and the insulating member has cooperatively located feet thereon which seat in the apertures.

Background of the invention The present invention relates to electrical circuit con trol device panel boards and, more particularly, to such panel boards which employ a baseupon which are supported a plurality of parallel extending conductors or busbars with insulating means therebetween.

.In such panel boards one of the significant problems constantly coped with is the need to reduce the size and cost. With reductions in spacing between the conductors, the problems of obtaining effective insulation therebetween have increased since there are minimum requirements for the distance of over-surface clearance between adjacent conductors and for air clearance between a conductor and an overlying contact arm of a different phase or polarity.

In an effort to provide adequate insulation between adjacent conductors, devices have been designed which space the conductors above the insulating material on the base or saddle rather than positively supporting it upon the upper surface of the insulating material since this would underlying one of the conductors being offset along the length of the conductors and the produce too small an over-surface clearance. Alternatively, devices have been fabricated which have provided complex configurations for the insulating support so as to avoid a planar surface. Various other devices have been constructed to provide an insulating member disposed over one busbar and supporting in insulated relationship therefrom the end of a contact arm extending from a busbar of different polarity or phase.

It is an object of the present invention to provide an electrical circuit control device panel board which may be relatively economically fabricated and supports the conductors directly upon the surface of the insulating material so as to achieve greater thermal conductivity.

It is also an object to provide such a panel board wherein the conductors may be relatively closely spaced with respect to each other and with respect to the underlying base or saddle so as to enable production of a relatively compact unit.

Another object is to provide such a panel board wherein novel insulating members are provided and support in insulated relationship from one conductor, contact arms extending from another conductor.

Summary of the invention It has now been found that the foregoing and related objects can be readily obtained in an electrical circuit control device panel board having a base or saddle with a generally planar portion upon which are disposed two layers of insulating material. A plurality of conductors are in turn directly supported upon the upper surface of the upper layer of insulating material and extend in substantially parallel spaced relationship. The second layer of insulating material has a plurality of apertures therein underlying each of the plurality of conductors and spaced therealong with the webs between apertures webs between apertures underlying the adjacent conductors. The apertures rare dimensioned and configured so as to extend beyond the side margins of'the conductors and toward the adjacent conductor. In this manner, the over-surface clearance or distance for travel along the upper surface of the second layer between adjacent conductors is increased substantially so that this distance may be considerably in excess of the actual spacing between adjacent conductors along a line drawn perpendicularly therebet'ween.

Although the layers of insulating material may be fabricated by other procedures to provide the desired apertures and configuration, it is far more preferable to fabricate the two layers from extruded or molded sheets of insulating material which are punched or otherwise formed with the desired apertures. Various synthetic plastics and fibrous materials impregnated with synthetic plastic may be employed for the insulating sheets. The

total thickness thereof must, of course, exceed minimum 7 standards for insulation between a conductor and an underlying conductive member.

Since it is most common to employ contact arms which extend from one conductor over another conductor, the panel board of the present invention utilizes insulating members which bridge the conductor over which the contact arms extend and provide an insulating support for the end thereof. These insulating members have side wall portions extending normally to the longitudinal axis of the conductors so as to provide increased insulating surface between the underlying conductor and the contact arm received therein.v Preferably these insulating members are formed with ribs on the upper surface thereof to form channels in which the contact arms may be snugly received. In some instances, it is desirable to employ insulating members of increased width providing a pair of channels, and in such member, a center wall portion is provided between the channels so as to ensure adquate insulating surface between the adjacent contact arms which may be of different polarity or phase. Most desirably, the insulating members are formed with depending bosses and legs providing passages for air between the bottom surface thereof and the underlying conductor in order to achieve optimum heat dissipation. For positively positioning the insulating members, they are provided with depending feet or pins which, seat in cooperatively located apertures to opposite sides of the conductor.

The exact number of conductors will vary with the intended application for the panel board. For some applications, a two-conductor system will be utilized with the insulating members disposed over one of the conductors to receive the contact arms extending from the other of the conductors. In other installations, a three-conductor system will be employed with the insulating members being disposed over the central conductor and receiving contact arms extending from both of the outer conductors.

The conductors or busbars may be secured to the upper surface of the insulating material by relatively simply configured insulating barrier blocks at either end thereof. The barrier blocks must, of course, provide means for positively engaging the conductors to ensure positive placement and this means may assume a number of forms. In one form the barrier block has apertures formed in the bottom surface thereof which receive pins or lugs on the conductors to achieve the desired retention and spacing. In another form, the barrier block is formedwith slots or channels in the bottom surface thereof which snugly seat the ends of the conductors. The barrier blocks themselves being formed of insulating material are secured directly to the underlying base or saddle by suitable fasteners.

The remainder of the panel board may employ generally conventional construction including terminal connectors on the conductors, a terminal board and various types of contact blades depending upon the type of circuit parallel devices to be assembled thereon. Generally, the panel board will be mounted within a suitable housing and means may be provided for adjusting the relative height of the panel board within that housing.

Brief description of the drawings FIGURE 1 is a plan view of an electrical circuit control device panel board assembly embodying the present invention showing two different modules of circuit breakers thereon and with the housing fragmentarily illustrated;

FIGURE 2 is a sectional view of the panel board assembly along the line 2-2 of FIGURE 1;

FIGURE 3 is a bottom perspective view of an insulating member; and

FIGURE 4 is an exploded perspective view of the panel board saddle assembly of FIGURE 1.

Detailed description of the illustrated embodiment Turning now to the drawings in detail, a panel board or load center embodying the present invention has a metal base or saddle generally designated by the numeral 2 and mounted in a suitable enclosure 4 which is only fragmentarily illustrated. As best seen in FIGURE 2, threaded fasteners 6 trapped at one end in the seats 8 of the enclosure 4 threadably seat in apertures at the corners of the saddle 2 to permit threaded adjustment of the spacing thereof from the front wall (not shown) of the enclosure 4.

The saddle 2 has a planar center portion 10 and a pair of upstanding parallel side wall portions 12 each with an outwardly projecting shelf portion generally designated by the numeral 13 and defined by an outwardly extending flange 14 and upstanding arms 16 spaced apart to define channels 18 therebetween. The arms 16 have apertures 20 formed therein and inwardly extending fingers 22 at the upper ends thereof to form substantially hook-shaped elements cooperating with the flange 14. The center portion 10 of the saddle also has a pair of rows of apertures 24 therein extending parallel to the side wall portions 12 and a pair of threaded bosses 26 at the ends thereof.

A first sheet of insulating material 30 lies upon the center portion 10 and has apertures 32 at its corners through which the threaded bosses 26 project. Two rows of de' pressions 34 align with the apertures 24in the saddle 2. A second sheet of insulating material 36 lies over the first sheet 30 and has apertures 38 at its corners aligned with the bosses 26 and with the apertures 32 in the first sheet 30. Two rows of apertures 40 in the center portion align with the apertures 24 and the depressions 34. Three rows 42, 44 and 46 of spaced elongated apertures provide webs 48, 50 and 52 along each row therebetween. The webs 50 of the central row 44 are offset along the length of the rows from the Webs 48, 52 of the outer rows 42, 46 so that a line drawn perpendicular to the rows from the webs 48, 52 will intersect one of the elongated apertures of the central row 44.

Mounted on the upper surface of the second sheet of insulation 36 are three parallel extending conductors or busbars 54, 56 and 58. The centralbusbar 56 is aligned with the center of the apertures in the central row 44 which are wider than the busbar 56, whereas the outer busbars 54, 58 only partially overlie the narrow apertures of the outer rows 42, 46 and extend over the surface of the sheet material outwardly thereof. At one end, the busbars 54, 56 and 58 have threaded connectors 60 which receive the ends of supply conductors (not shown).- Mounted in spaced relationship along the length of the outer busbars 54, 58 and extending nOImally thereto over the central busbar 56 are contact arms 62 with an upward offset therein to increase the air spacing from the upper insulating sheet 36. At their free or inner ends, the contact arms 62 have a pair of transverse blade portions 64, 66 extending parallel to the busbars 54, 56, 58 and a central blade portion 68 of considerably greater height intersecting the blade portions 64, 66. As best seen in FIGURE 1, the center busbar 56 also has mounted thereon contact members 70 similarly providing transverse blade portions 72, 74 and a center blade portion 76.

The busbars 54, 56 and 58 are secured in assembly by the barrier blocks 78, which are molded from insulating material and fastened to the saddle 2 by threaded fasteners 82 extending through the apertures 32 and 38 in the sheets 30, 36 of insulation and engaged in the threaded bosses 26. As best seen in FIGURE 4, the barrier block 78 has three spaced recesses 84 in its bottom surface which receive and seat pins 86 on the upper surfaces of the busbars 54, 56 and 58 so as to locate positively that end thereof. The barrier block 80 has three spaced slots 88 in its lower surface which receive the opposite ends of the busbars so as to locate positively both ends of the busbars.

The contact arms 62 are insulated from the central busbar 56 over which they extend by molded insulating members generally designated by the numerals 90' and 92. The insulating member 90 receives a single contact arm 62 and the insulating member 92 is approximately double the width of the member 90 and receives a pair of contact arms 62. As best seen in FIGURE 3, both insulating members 90, 92 have base portions 94 with a central boss 96 seating on the busbar 56 and depending legs 98 to provide support therefor outwardly from the busbar 56. To ensure proper placement and provide retention, the legs 98 have feet or pins 100 thereon which extend into the apertures 40 of the second insulating sheet 36 and depressions 34 of the first insulating sheet 30. The boss 96 and legs 98 enable air to circulate between the insulating members 90, 92 and busbar 55. Upstanding ribs 102 are molded on the upper surface of the base portions 94 and extend normally to the busbar 56 so as to provide one channel 104 receiving and seating a contact arm 62 in the member 90 and a pair of channels 104 receiving a pair of contact arms 62 in the member 92. Side wall portions 106 extending normally to the busbar 56 are also provided to increase the insulating surface between the contact arms 62 and the busbar 56 and to support circuit breakers received therein. The insulating member 92 also has a center Wall portion 108 between the two channels 104 thereof to provide insulating surface between the contact arms 62 of'different polarity and to provide support for the circuit breakers received therein.

In operative assembly, a plurality of circuit control devices of two different widths or modules may be mounted on the panel board of the illustrated embodiment. The control devices are generally designated by the numerals 110, 116 and of generally conventional circuit breaker construction with operating handles 111, 117. The larger module breaker 110 is of conventional construction and has an insulating housing 112 formed with a recess 114 in the lower portion of its rear or outer end which receives a finger 22 of the side wall portion 12 of the saddle to locate that end positively. At the bottom of its front or inner end, it has a pair of contact jaws (not shown) extending parallel to its longitudinal axis which clamp on a central blade portion 76 of a contact member 70 in the assembly illustrated in FIGURE 1.

The smaller module breaker generally designated by the numeral 116 has an insulating housing 118 formed with one or a pair of spaced apart rearwardly projecting tongues 120 on its rear or outer end for seating in the channels 18 between arms 16 or in the apertures 20 in-the arms 16. At the bottom of its front or inner end, it has a pair of contact jaws (not shown) extending normally to the longitudinal axis which clamp on transverse blade portions 72, 74 of a contact member 70 in the illustrated assembly.

It will be appreciated that various combinations of the smaller and larger module breakers 110, 116 may be assembled upon contact arms 62 and contact members 70. Two small module breakers 116 may be assembled in opposed relationship as illustrated, or a pair of small module breakers 116 may be assembled in sideby-side relationship to opposite sides of a central blade portion. Two large module breakers 116 may be assembled in opposed relationship as illustrated, or such a breaker may be assembled in opposed relationship with one or two small module breakers 116.

In operation of the device, it can be seen that the elongated apertures 42, 44 and 46 interrupt the surface of the insulating sheet 36 upon which the busbars 54, 56 and 58 are disposed. For an arc to travel along the surface from an outer busbar 54, 58 to the central busbar 56, it must travel from the web portion 48 or 52 to the web portion 50 of the central row 44 of elongated apertures since the apertures underlying the several busbars extend beyond the adjacent side margins of the busbars. As a result, the fiat surface of the insulating sheet 36 readily exceeds the minimum over-surface clearance required for panel board assemblies. The lower insulating sheet 30 ensures adequate insulation between the busbars and the center portion of the saddle 2, particularly at the elongated apertures 42, 44 and 46. The insulating members 90, 92 provide insulation between the contact arms 62 and the central busbar 56 as well as support for the sides of the breakers. Where two adjacent contact arms 62 extend from outer busbars 54, 58, the insulating member 92 is employed and provides an insulating center wall portion 108 therebetween.

Thus, it can be seen that the present invention provides a panel board of greater thermal conductivity since the busbars are mounted directly on the surface of sheetlike insulating material. In addition, this minimizes the depth required for the interior of the panel board housing to permit more compact units. By use of punched sheets of insulating material, the panel board may be fabricated relatively economically and easily, and special 6 insulating supports may be avoided. The insulating members provide air circulation between the central conductor and the bottom surface thereof, and insulating surface between the central conductors and the contact arms.

While the invention has been illustrated in only one embodiment, it will be readily apparent that many modifications thereof may be made, and I therefore intend by the appended claims to cover all such modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In an electrical circuit control device panel board, the combination comprising:

(a) a base having a generally planar portion;

(b) a first layer of insulating material on said planar portion of said base;

(c) a second layer of insulating material on said first layer; and g (d) a plurality of conductors on said second layer extending in substantially parallel spaced relationship, said second layer having a plurality of apertures therein underlying each of said plurality of conductors and spaced therealong, said apertures extending beyond side margins of said conductors toward adjacent conductor, webs between apertures underlying one of said conductors being oifset along the length of conductors from the webs between apertures underlying the adjacent conductors whereby the distance for travel along the upper surface of said second layer between adjacent conductors is increased substantially.

2. The panel board of claim sheets of insulating material.

3, The panel board of claim 1 wherein said plurality of conductors consists of three parallel spaced conductors, the webs between apertures along the central conductor being offset along the length of said conductors from the webs between apertures along the outer conductors.

4. The panel board of claim 1 wherein an insulating member bridges one conductor and a contact arm having one end attached to another conductor extends normally thereto with its other end disposed on said insulating member, said insulating member having side wall portions providing insulating surface between said contact arm and said one conductor.

5. The panel board of claim 4 wherein said insulating member has upstanding ribs on the upper surface thereof providing a channel seating said contact arm.

6. The panel board of claim 4 wherein said insulating member has upstanding ribs 0n the upper surface thereof providing a pair of channels seating a pair of contact arms and an upstanding center wall portion between said channels providing an insulating barrier therebetween.

7. The panel board of claim 1 wherein said conductors are secured against the upper surface of said second layer by a pair of insulating members extending thereacross adjacent the ends thereof and removably engaged with said base.

8. The panel board of claim 4 wherein said second layer has a plurality of apertures therein on opposite sides of said one conductor and wherein said insulating member has feet depending therefrom to opposite sides of said one conductor and seated in said plurality of apertures for positioning thereof.

9. In an electrical circuit control device panel board, the combination comprising:

(a) a base having a generally planar portion;

(b) a first sheet of insulating material on said planar portion of said base;

(c) a second sheet of insulating material on said first sheet;

(d) three conductors on said second sheet extending in substantially parallel spaced relationship, said second sheet having a plurality of apertures therein underlying each of said conductors and spaced therealong,

1 wherein said layers are said apertures underlyir. g the central conductor being of greater width than said central conductor and extending beyond the side margins thereof and said apertures underlying the outer conductors extending beyond the side margins of said outer conductors toward said central conductor, Webs between apertures underlying said central conductor being offset along the length of the conductors from webs between apertures underlying the outer conductors whereby the distance to travel along the upper surface of said second sheet between adjacent conductors is increased substantially.

(e) an insulating member bridging the central conductor and having side wall portions extending normally to said conductors; and

(f) a contact arm having one end attached to one of said outer conductors and having its other end disposed on said insulating member between said side wall portions and providing a contact blade portion.

' 10. The panel board of claim 9 wherein said second sheet has a plurality of apertures therein on opposite sides of said central conductor and wherein said insulating member has feet depending therefrom about said central conductor and seated in said apertures for positioning" thereof.

11. The panel board of claim 9 wherein said insulating member has upstanding ribs on the upper surface thereof providing a pair of channels seating a pair of contact arms and an upstanding center wall portion between said channels providing an insulating barrier therebetween.

References Cited UNITED STATES PATENTS 4 2,862,995 12/1958 Hercules 317-119" 2,986,676 5/1961 Edmunds 3171 19 ROBERT K, SCHAEFER, Primary Examiner.

v H. O. JONES, Assistant Examiner. 

